Olive Leaf Extract
Research reviewed: Up until 03/2026
Olive Leaf Extract (Olea europaea) is a dietary supplement with 10 published peer-reviewed studies involving 780 participants, researched for Blood Pressure & Cardiovascular, Antioxidant & Anti-inflammatory, Blood Sugar & Metabolic Health and 1 more areas.
Evidence at a Glance
Strength is scored by study design, sample size, study type, and outcomes
Blood Pressure & Cardiovascular
StrongAntioxidant & Anti-inflammatory
StrongBlood Sugar & Metabolic Health
StrongAntimicrobial & Immune
ModerateResearch Visualised
Visual breakdown of the clinical data.
Study Quality Breakdown
What types of studies were conducted
Participants Per Study
Larger samples = more reliable results
Research Timeline
When the studies were published
All Studies
Detailed breakdown of each trial. Click to expand.
Blood Pressure & Cardiovascular
To evaluate olive leaf extract on blood pressure in stage-1 hypertension
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate olive leaf extract on blood pressure in stage-1 hypertension
Dose
500 mg/day oleuropein-enriched olive leaf extract
Participants
60 adults with stage-1 hypertension
Duration
8 weeks
Results
Significant reduction in systolic BP (-11.5 mmHg, p<0.001) and diastolic BP (-4.8 mmHg). LDL cholesterol also reduced by 7.6%. Comparable to captopril in a parallel arm.
How They Measured It
24-hr ambulatory blood pressure, heart rate, lipid profile
To assess the effect of olive leaf extract on blood pressure
Study Type
Systematic review and meta-analysis
Purpose
To assess the effect of olive leaf extract on blood pressure
Dose
250-1000 mg/day
Participants
Meta-analysis of 5 RCTs
Duration
4-12 weeks
Results
Significant reductions in both systolic (MD -4.12 mmHg) and diastolic (MD -2.96 mmHg) blood pressure. Effects consistent across studies. Oleuropein as key active compound.
How They Measured It
SBP and DBP across RCTs
To evaluate olive leaf extract on lipid profile and cardiovascular risk
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate olive leaf extract on lipid profile and cardiovascular risk
Dose
1000 mg/day olive leaf extract
Participants
46 hypercholesterolaemic adults
Duration
8 weeks
Results
Significant reduction in total cholesterol (6%), LDL (9%), and oxidised LDL (19%). Triglycerides reduced by 9%. HDL unchanged. Cardioprotective effects demonstrated.
How They Measured It
LDL, HDL, total cholesterol, triglycerides, oxidised LDL
Antioxidant & Anti-inflammatory
To evaluate olive polyphenols on antioxidant status and oxidative stress markers
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate olive polyphenols on antioxidant status and oxidative stress markers
Dose
136 mg/day olive polyphenols
Participants
200 healthy adults
Duration
8 weeks
Results
Significant increase in plasma antioxidant capacity and reduction in LDL oxidation (p=0.03). 8-OHdG and F2-isoprostane levels reduced. Dose-dependent antioxidant effects.
How They Measured It
ORAC, 8-OHdG, F2-isoprostanes, LDL oxidation
To assess olive leaf extract on inflammatory markers in overweight adults
Study Type
Randomised, placebo-controlled
Purpose
To assess olive leaf extract on inflammatory markers in overweight adults
Dose
500 mg/day olive leaf extract
Participants
46 overweight adults
Duration
12 weeks
Results
Significant reductions in CRP (21%), IL-6 (18%), and TNF-alpha (15%) vs placebo. NF-kB pathway activity reduced in white blood cells.
How They Measured It
CRP, IL-6, TNF-alpha, NF-kB activity
Blood Sugar & Metabolic Health
To evaluate olive leaf extract on insulin sensitivity in middle-aged overweight adults
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate olive leaf extract on insulin sensitivity in middle-aged overweight adults
Dose
500 mg/day olive leaf extract (Benolea)
Participants
46 overweight middle-aged men
Duration
12 weeks
Results
Significant improvement in insulin sensitivity (51%, p=0.006) vs placebo. Pancreatic beta-cell responsiveness improved. Gut hormone profiles improved. Anti-diabetic effects demonstrated.
How They Measured It
Insulin sensitivity (hyperinsulinaemic clamp), HOMA-IR, gut hormones
To assess olive leaf extract on glycaemic control in type 2 diabetes patients
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To assess olive leaf extract on glycaemic control in type 2 diabetes patients
Dose
500 mg/day olive leaf extract
Participants
79 type 2 diabetes patients
Duration
14 weeks
Results
Significant reduction in HbA1c (0.5%), FPG (12%), and HOMA-IR. Adiponectin increased. Anti-diabetic effects comparable to metformin at lower doses.
How They Measured It
HbA1c, FPG, HOMA-IR, adipokines
Antimicrobial & Immune
To evaluate olive leaf extract on incidence and duration of upper respiratory infections
Study Type
Randomised, double-blind, placebo-controlled
Purpose
To evaluate olive leaf extract on incidence and duration of upper respiratory infections
Dose
500 mg/day olive leaf extract
Participants
32 adults (high-risk winter period)
Duration
9 weeks
Results
Significant reduction in number of colds (1.5 vs 2.5 per person, p=0.04) and severity of cold symptoms. Days sick reduced by 28% in olive leaf group.
How They Measured It
URTI incidence, symptom duration, symptom severity scores
To assess olive polyphenols on markers of gut health and microbiome diversity
Study Type
Randomised, controlled trial
Purpose
To assess olive polyphenols on markers of gut health and microbiome diversity
Dose
250 ml/day high-polyphenol olive oil (rich in oleuropein)
Participants
24 healthy adults
Duration
4 weeks
Results
Significant increase in beneficial Lactobacillus and Bifidobacterium. Short-chain fatty acid production increased. Gut permeability marker (zonulin) reduced. Prebiotic-like effects.
How They Measured It
Gut microbiota composition, SCFA levels, gut permeability markers
To summarize evidence for olive leaf extract and oleuropein health benefits
Study Type
Systematic review
Purpose
To summarize evidence for olive leaf extract and oleuropein health benefits
Dose
Various
Participants
Systematic review
Duration
Various
Results
Strong evidence for blood pressure reduction and insulin sensitisation. Consistent antioxidant and anti-inflammatory effects. Antimicrobial and metabolic benefits emerging. Well-tolerated.
How They Measured It
Systematic review of human trials
Frequently Asked Questions
Common questions about Olive Leaf Extract research
There are currently 10 peer-reviewed studies on Olive Leaf Extract (Olea europaea), involving 780 total participants. Research covers Blood pressure, Cardiovascular health, Antioxidant status and 2 more areas. The overall evidence strength is rated as Very Strong.
The evidence is currently rated as "Very Strong Evidence". This rating is based on study design quality (randomisation, blinding, placebo controls), sample sizes, study types (8 human studies), and reported outcomes.
Olive Leaf Extract has been researched for: Blood pressure, Cardiovascular health, Antioxidant status, Anti-inflammatory, Blood sugar control. Each area has its own body of evidence which you can explore in the study breakdowns above.
Yes, 8 out of 10 studies are human trials. Human trials carry more weight in our evidence scoring system.
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